The effect of algal biomass supplementation in maternal diets on piglet survival in two housing systems

Current developments in the pig industry pose increased challenges for piglet survival as a result of selection for increased prolificacy and welfare pressures to abolish the use of farrowing crates. The effect of supplementation of the maternal diet with algal biomass, containing the essential fatty acid docosahexaenoic acid (DHA), on the performance of sows and their piglets farrowing in two different housing conditions was studied using a 3×2 factorial experiment. A control diet was compared to 2 levels of DHA supplementation from algal biomass (0.03% and 0.3% DHA, delivered by 1.5 g/kg and 15 g/kg algal biomass) during the last 4 weeks of pregnancy and lactation, using 60 sows (mean parity 4.7 sem 0.32) in two different farrowing systems (farrowing crate and PigSAFE farrowing pen). Two-way analyses of variance showed no statistically significant interactions between dietary treatment and housing system. Piglet survival and growth did not differ between the crate and pen systems. Litter size (13.1 sem 0.42) and piglet birthweight (1.45 sem 0.047 kg) did not differ between dietary treatments, but the number of stillborn piglets per litter was reduced with increasing DHA supplementation (1.13, 0.67, 0.25, sem 0.205, P=0.014, with litter size covariate). This was despite an increase in farrowing duration of the sows with increased DHA supplementation (150.3, 195.2 and 216.2 sem 13.6 min, P=0.02). The vitality of the piglets, as described by the latency (min) of the piglets to stand (1.92, 1.44 and 1.17, sem 0.09, P<0.001), to reach the teat (21.55, 15.71 and 11.20, sem 1.35, P<0.001) and to suckle (25.66, 19.14 and 14.83, sem 1.40, P<0.001), was also improved with increased supplementation of DHA. Mortality of liveborn piglets in the first 3 days, and number weaned per litter (after fostering) were unaffected by treatment, as were sow weight and backfat loss in lactation. However, piglet weaning weight was reduced by DHA supplementation (by up to 12%). The mechanism for the reduction in stillbirth should be further investigated.